Control system for wire-tying apparatus



Sept. 27, 1966 M, HALL 3,274,921

CONTROL SYSTEM FOR WIRE-TYING APPARATUS Filed Feb. 10, 1965 Q76 END 32 INVENTOR MARC/ AND B. HALL Afro/nay United States Patent 3,274,921 CONTROL SYSTEM FOR WlltE-TYHNG APPARATUS Marchand E. Hall, Olympia Fields, lllL, assignor to United States Steel Corporation, a corporation of Delaware lFilcd Feb. 10, 1965, tier. No. 431,647 6 Claims. (Cl. lllll4) The present invention relates generally to control systems and, more particularly, has as its primary object the provision of an improved control system especially suitable for controlling the automatic operation of a wiretying apparatus.

It is a more specialized object of the invention to provide an electr c-hydraulic control system whereby the various operations of a wire-tying apparatus are performed automatically in proper sequence.

It is another object of the invention to provide an electro-hydraulic control system of the character set forth by the above statement of object which includes a novel combination of a free-flowing valve, a flow-restricting orifice and a variable sequence valve to accomplish two different functions of an apparatus at different times.

These and other objects will become more apparent after referring to the following specification and attached drawing.

In the drawing affixed to this specification and forming part thereof, a wire-tying apparatus embodying the control system of the invention is illustrated diagrammatically in perspective by way of example.

The wire-tying apparatus shown in the drawing is of the type shown and described in detail in co-pending application Serial No. 431,618, filed February 10, 1965, and will be shown and described herein only to the extent necessary for a clear understanding of the control system of the invention.

The wire-tying apparatus shown in the drawing, designated generally by reference numeral 2, includes a pair of pinch rolls 4, operated by a hydraulic motor 6, for feeding tie wire W through a twister pinion 8, past a gripper 10, around a continuous guide track 12 and through the twister pinion a second time and then into the jaw of the gripper. Upon reverse rotation of the motor 6, pinch rolls 4 function to retract the tire wire, strip it out of the guide track and tension it around a package P within the guide track. After the tie wire has been tensioned around the package, a sector gear 14, in mesh with the twister pinion 8, is actuated to rotate the pinion and twist the overlapped ends of the tie wire to gether. The knot thus formed is then cut free from the supply wire and ejected from the pinion.

The sector gear 14 of the wire'tying apparatus is operated by a roller 16 carried by a cam plate 28, which, in turn, is attached to and actuated by a piston rod 20 of a double-acting hydraulic pressure cylinder 22. A pivoted jaw 24 of the gripper 10, which cooperates with a fixed jaw 25, is attached to and actuated by the piston rod 26 of a double-acting hydraulic pressure cylinder 28.

The control system of the invention is shown schematically in the single figure of the drawing and includes a hydraulic pump 30 connected directly with and driven by an electric motor 32 to circulate hydraulic fluid under pressure throughout the system from a reservoir 34. The pump 30 is connected with a reversing, directional, threeposition, four-way valve 36, operated in one direction by a feed electric solenoid 38 and in the other direction by a tension solenoid 46.

A fluid line 42 is connected with the feed outlet port of valve 36 at one end and extends therefrom to a juncture 44 with two lines 46 and 48. Line 46 extends from the juncture to the head end of cylinder 28, while line 48 extends from the juncture to the feed side of "ice hydraulic motor 6. The line 48 is also connected with head end of cylinder 22 by a line 59.

A line 52 is connected with valve 36 at its tension outlet port at one end and extends therefrom to a juncture 54 with lines 56 and 53. Line 56 extends from juncture 54 to the rod end of cylinder 22, while line 58 extends to a juncture 66 with lines 62 and 64. Line 62 extends from juncture to the tension side of hydraulic motor 6, and line 64 extends to the rod end of cylinder 28.

A check valve 66 is provided in the line 56, and a variable sequence valve 68 is connected in circuit with lines 56 and 58. Check valve 66 permits relief flow of hydraulic fluid from the rod end of cylinder 22 but prevents flow of fluid directly from valve 36 to the rod end of cylinder. As will become apparent, flow of hydraulic fluid to the rod end of cylinder 22 occurs only when variable sequence valve 68 is open. A flowrestricting orifice 70 is provided in the line 62, and a normally-closed, free-flow, two-way valve 72 is provided to bypass the orifice '70 at certain stages of operation, as will become apparent. Valve 72 is operated by a solenoid 74.

Operation Before the start of an operating cycle to apply a tie around the package P which has been moved into position within the guide track 12, the wire W has been fed into the apparatus by the pinch rolls 4, driven through the twister pinion 8, around the track, through the twister pinion again and then into the gripper it). Initially, all of the valves and elements of the control system of the invention are positioned as indicated in the single figure of the drawing. It will be noted that tie wire has been fed into the wire-tying apparatus prior to the start of the tying cycle described hereinafter.

To effect a tying cycle after the tie wire has been fed into the apparatus as described, switches 76 and 78 are closed and the following sequence of operations occurs:

1) Switch 76 remains closed and electric motor 32, connected in circuit therewith, runs continuously during the tying cycle.

(2) Closing of switch 73 completes a circuit to a relay coil 8t) causing it to become energized and its two normally-open contacts 82 and 84 to close and remain closed after switch 78 is released.

(3) Closing of contact 82 of relay 8t) completes a circuit, through a normally-closed contact 86 of a switch 68, to solenoid 46 causing the spool of valve 36 to shift to the left.

(4) Closing of contact 84 of relay 86 completes a circuit, through the normallyopen, held-closed contact of a switch 90, to the solenoid '74 to shift the spool of two-way valve 72 to the left and open the valve.

(5) Hydraulic fluid from valve 36 then flows through lines 52, 58 and 64 to the rod end of cylinder 28 to retract its piston rod 26 and pivot the jaw 24} of gripper it) toward the fixed jaw 25 and grip the end of wire W therebetween. At the same time, hydraulic fluid flows through lines 52 and 58, through open-valve 72, bypassing orifice 7t and thence through line 62 to the tension side of hydraulic motor 6. Motor 6 then drives pinch rolls 4 to retract the wire W and tension it around the package P.

(6) As the wire W draws around the package and tightens, the pressure in the system increases until it reaches a predetermined pressure value to which variable sequence valve 68 has been preset. Then the sequence valve opens and allows hydraulic fluid to flow through line 56 to the rod end of cylinder 22 to retract the piston rod 20 thereof.

(7) As the piston rod '20 retracts, cam plate 18 starts to move forward, opening limit switch 96, which is in circuit with solenoid 74. Opening of switch 96 causes de-energization of valve solenoid '74 and closing of valve 72. After the valve 72 closes, the orifice 70 permits a slight flow of hydraulic fluid to the tension side of the motor 6 through line 62 so that the wire W is kept taut during the knotting sequence.

(8) As the piston rod 20 continues to retract, sector gear 14 is rotated in clockwise direction, causing twister pinion 8 to rotate 3% times and form a twist knot in the portions of the wire W overlapped in the slot of the twister pinion. Movement of the cam plate after the knot has been formed causes, through elements not shown, the completed knot to be cut from the supply wire and ejected from the twister pinion. Ejection of the completed knot causes open switches 93 and 160 to close since they are then removed from engagement with the wire.

(9) The combination of roller 16 and the radial slot in sector gear 14 permits the piston rod 20 to continue to retract after sector gear 14 has reached its forward end of travel. This causes continued rotation of cam plate 18 until a pin 92 projecting from the cam plate engages and trips the actuating arm 9 of the double-contact switch '88. This causes normally-closed contact 86 of switch 88 to open and break the circuit to relay coil 80 causing contacts 82 and 84 of relay 80 to open and remain open. The opening of contact 82 de-energizes solenoid 4-0. Opening of contact 84 of relay 86 has no effect since the previous opening of switch 96 caused deenergization of solenoid 74 to close switch 72.

(10) Engagement of the arm 94 by pin 92 also causes closing of the normally-open contact 96 of switch 88 to complete a circuit, through the closed switch 160, to a relay coil 162 and to solenoid 38. Energization of relay coil 102 causes its two normally-open contacts to close and remain closed. Energization of solenoid 38 causes shifting of the spool of valve 36 to the right. Shifting of the spool of valve 36 to the right causes hydraulic fluid to flow through lines 42, 43, 50 and 46 to the head end of cylinders 22 and 23 to open the gripper 10 and return cam plate 18 to original position.

(11) When the cam plate 18 returns to its original position, switch 90 is closed. Closing of switch 96 completes a circuit through the closed switch 98 and the closed relay contact 166 causing energization of solenoid 74 and opening of valve 72. This permits hydraulic fluid to flow through hydraulic motor 6 from line 48 and cause it to rotate pinch rolls 4 in the feed direction to feed more tie wire to the wire-tying apparatus preparatory to the next tying operation.

(12) During the wire-feeding sequence, as the leading end of the Wire W approaches the twister pinion 8 the second time, it trips and opens limit switch 98, which is in circuit with solenoid 74, to cause de-energization of solenoid 74 and closing of valve 72. With valve 72 closed, the hydraulic fluid flowing from hydraulic motor 6 through line 62 must flow through the flow-restricting orifice 70. As a result, the last few inches of feed are accomplished at a slower speed.

(13) After the leading end of the wire has traveled around the track and passed through the gripper, it trips and opens limit switch 160 which causes de-energization of relay coil 102 so that all circuits except that to pump motor 32 are broken. The spool of valve 36 then centers and pump idles, bypassing hydraulic fluid through valve 36 and back into reservoir 34.

Thus, it will be obvious that the unique and novel manner in which the combination of the free-flowing, twoway valve 72, the flow-restricting orifice 7t) and the variable sequence valve 68 is utilized in the control system of the invention achieves automatic operation of multistep apparatus in proper sequence with more accuracy, higher degree of control and greater uninterrupted continuous operation than was possible heretofore. A sequence valve used in conventional manner would allow flow to the hydraulic motor 6, causing tensioning, and prevent hydraulic fluid flow to the knotter cylinder 22 until the pressure setting of the sequence valve was reached. Then the pressure in both the hydraulic motor 6 and the cylinder 22 would be controlled only through the resistance of cylinder 28, if above the pressure value setting of the sequence valve. This could cause excessive tension and also cause the tire wire to tension out of the feed-and-tension pinch rolls of the apparatus as soon as the knotter reached the point in the cycle when the completed knot is cut (before ejection).

In operation of the control system of the invention, when variable sequence value 68 opens, the piston rod 20 removes a short distance and starts counterclockwise movement of cam plate 18 which latter movement causes opening of switch and closing of valve 72. This then allows only a small amount of hydraulic fluid to reach the hydraulic motor 6 through the orifice 70', and the pressure-drop across the orifice prevents excessive tensioning. The reduced flow of hydraulic fluid through the orifice 76 during knotting compensates for leakage of fluid through the motor 6 and keeps the wire taut.

It will be noted that the same valve 72 and orifice 70 of the control system of the invention are utilized a second time during operation of the system for a different purpose. During feed of tie wire W into the apparatus as described above, the wire is fed around the track at a high rate of speed when the solenoid-operated valve 72 is open. If the wire were fed at such high rate of speed during the entire feeding sequence, the leading end thereof would extend beyond the gripper 10 an objectionable amount after the feeding sequence was completed. In the operation of the control system of the invention, the valve-operating solenoid 74 is de-energized the valve 72 is closed as the leading end of the wire approaches the twister pinion 3 a second time. Hydraulic fluid flowing through the motor 6 then must flow through the orifice 70, which reduces the flow considerably so that the speed of motor 6, and, consequently, the speed of the wire being fed, is greatly reduced. This reduced speed makes it possible to stop the feeding more accurately and minimize variations in the length of wire extending beyond the twister or knot portion of a tie.

Although I have shown the control system of the invention as being used in conjunction with wire-tying apparatus which includes joining means in the form of a twister pinion, it will be understood that the system of the invention can be used in conjunction with wire-tying apparatus which includes joining means other than a twister pinion, for example, a seal-applying joining means.

It is not intended to limit the scope of this invention to the use of the control system described for operating a wire-tying apparatus, but rather to include any use to which the invention lends itself and to any modification of the invention within the scope of the claims hereinafter recited.

I claim:

1. A control system for a wire-tying apparatus including a guide track for the wire, joining means forming a portion of said track, a gripper jaw pivoted adjacent the far end of said means in the direction in which wire is fed through the track, pinch rolls eflective to feed wire into said track and on reversal to tension a tie wire about an article within said track, said system comprising a reversible fluid motor driving said pinch rolls, a fluid pressure cylinder connected with said joining means, a fluid circuit connected to said motor and to said cylinder, a reversing valve in said circuit, first means actuating said valve to direct fluid toward said motor, and to said cylinder to operate said cylinder to move said joining means to initial operating position, a fullflow valve in said fluid circuit between said reversing valve and said motor, means for operating said full-flow valve, means operated by completion of the movement of said joining means to initial operating position connected with said full-flow valve-operating means effective to actuate the same to open said full-flow valve after said joining means reaches initial operating position whereby said motor is operated to drive said pinch rolls in the direction to feed a tie wire through said joining means, around said track and through said joining means a second time, second means actuating said reversing valve to direct fluid to said motor to operate said motor to drive said pinch rolls in the reverse direction to retract said tie wire from said track, and to said fluid pressure cylinder to operate the same to actuate said joining means in a direction to form a joint, a pressure sequence valve in said fluid circuit between said reversing valve and said fluid pressure cylinder adapted to effect operation of said joining means only on the increase of the pressure in said fluid circuit to a predetermined value.

2. A control system as defined by claim 1 characterized by a flow-restricting orifice in said fluid circuit, a bypass around said orifice, said full-flow valve being in said by-pass, said full-flow valve-operating means comprising a solenoid, and means actuated by the second passage of said tie Wire into said joining means in electrical circuit with said solenoid eflective to de-energize said solenoid to close said full-flow valve.

3. A control system as defined by claim 1 characterized by a flow-restricting orifice in said fluid circuit, a by-pass around said orifice, said full-flow valve being in said by-pass, said full-flow valve operating means comprising a solenoid, and said means operated by completion of the movement of the joining means to initial operating position being a switch in electrical circuit with said solenoid.

4. A control system as defined by claim 1 characterized by switch means actuated by final movement of said joining means in joint-forming direction, said switch means being in electrical circuit with said first and said second reversing-valve actuating means, said switch means being adapted when actuated to de-energize said second reversing-valve actuating means and energize said first reversing-valve actuating means.

5. A control system as defined by claim 1 characterized by a switch in electrical circuit with said second reversing-valve actuating means effective to operate the same after said tie wire has been fed through said joining means, around said track and through said joining means a second time.

6. In a control system for a wire-tying apparatus as defined by claim 1 characterized by a fluid pressure cylinder connected with said gripper jaw for actuating the same, said last-mentioned cylinder being in said fluid circuit between said reversing valve and said gripper jaw in parallel with said motor whereby said last-mentioned cylinder is operated to open said gripper jaw when said first reversing-valve actuating means actuates said reversing valve to direct fluid towards said motor, and to close said gripper jaw when said second reversing-valve actuating means actuates said reversing valve to operate said motor to drive said pinch rolls in the reverse direction to retract said tie wire from said track.

References Cited by the Examiner UNITED STATES PATENTS 2,707,430 5/ 1955 Leslie et a1. -26 X 2,908,215 10/ 1959 Fawcett 100--26 3,116,681 1/1964 VandeBilt 10026 3,120,171 2/1964 Hall et al. 10026 3,126,686 3/1964 Kobylanski et al. 53198 3,139,813 7/1964 Hall et al. 1004 3,146,695 9/1964 VandeBilt 100-4 3,179,037 4/1965 Cranston et al. 1004 3,183,824 5/1965 (look 100--4 3,215,064 11/1965 Koehler 10025 X WALTER A. SCHEEL, Primary Examiner.

BILLY J. WILHI'I E, Examiner. 

1. A CONTROL SYSTEM FOR A WIRE-TYPING APPARATUS INCLUDING A GUIDE TRACK FOR THE WIRE, JOINING MEANS FORMING A PORTION OF SAID TRACK, A GRIPPER JAW PIVOTED ADJACENT THE FAR END OF SAID MEANS IN THE DIRECTIION IN WHICH WIRE IS FED THROUGH THE TRACK, PINCH ROLLS EFFECTIVE TO FEED WIRE INTO SAID TRACK AND ON REVERSAL TO TENSION A TIE WIRE ABOUT AN ARTICLE WITHIN SAID TRACK, SAID SYSTEM COMPRISING A REVERSIBLE FLUID MOTOR DRIVING SAID PINCH ROLLS, A FLUID PRESSURE CYLINDER CONNECTED WITH SAID JOINING MEANS, A FLUID CIRCUIT CONNECTED TO SAID MOTOR AND TO SAID CYLINDER, A REVERSING VALVE IN SAID CIRCUIT, FIRST MEANS ACTUATING SAID VALVE TO DIRECT FLUID TOWARD SAID MOTOR, AND TO SAID CYLINDER TO OPERATE SAID CYLINDER TO MOVE SAID JOINING MEANS TO INITIAL OPERATING POSITION, A FULLFLOW VALVE IN SAID FLUID CIRCUIT BETWEEN SAID REVERSING VALVE AND SAID MOTOR, MEANS FOR OPERATING SAID FULL-FLOW VALVE, MEANS OPERATED BY COMPLETION OF THE MOVEMENT OF SAID JOINING MEANS TO INITIAL OPERATING POSITION CONNECTED WITH SAID FULL-FLOW VALVE-OPERATING MEANS EFFECTIVE TO ACTUATE THE SAME TO OPEN SAID FULL-FLOW VALVE AFTER SAID JOINING MEANS REACHES INITIAL OPERATING POSITION WHEREBY SAID MOTOR IS OPERATED TO DRIVE SAID PINCH ROLLS 